1. Field of the Invention
The present invention generally relates to a punching device for punching out pieces from thin plate material and to a punching unit in which the punching device is positioned.
2. Discussion of Relevant Information
Conventional punching devices used for punching holes having round, rectangular or ovular shapes exist for making the holes in desired locations in thin plate material, e.g., in circuit boards, flexible films, or metallic foil; in these devices, a plurality of punching units with punches are used to punch holes of desired shapes and are positioned immediately above each of the punching positions on a working surface on which the thin plate-like workpieces are respectively positioned.
In order to punch thin plate material with such punching devices, the punches in each of the punching units are simultaneously moved downwardly to effect a punching operation after respective workpieces are mounted on the working surface, and, thereafter, holes of desired shapes are punched at desired positions on the workpiece.
However, since punching devices as described above are formed such that each of the punching units is fixed immediately above the punching position of each workpiece, it is necessary to remove and replace each of the punching units with a new one in order to change the shape of the holes to be punched, or the punching position of the punching units, and thus a time loss caused by replacement of one punching unit would substantially decrease the overall working efficiency of the apparatus.
Furthermore, since punches in the punching units used in these punching devices cannot be replaced within a short period of time, it has been necessary to effect complete replacement of the punching units themselves, even in situations in which only the punch itself needs to be replaced with a punch of different shape.